This invention relates to analysis employing ozone as a reactant and is especially concerned with improvements in nitrogen oxides analyzers in which ozone is generated for chemiluminescent reactions.
One type of nitrogen oxides analyzer now in wide use employs the chemiluminescent reaction of nitric oxide (NO) and ozone (O.sub.3). The ozone can be produced from ambient air by means of an electric discharge type ozone generator. The reaction between the ozone and the nitric oxide in a sample occurs in a reactor chamber having a transmissive window through which light produced by the chemiluminescent reaction is transmitted to a detector, commonly a photomultiplier tube (PMT). Several problems in such analyzers have been observed, namely, higher than normal zero based output, erratic response to sample or span gases, particularly during winter periods, and the need for frequent maintenance to keep the reactor chamber clean and to replace parts that have deteriorated. Although these deficiencies have been known for some time, the reasons for the problems have not been known, and the problems have resisted practical solution.